Rationale for Ada 2012

9.3.7 Exceptions as types

This proposal originally arose out of a workshop
organized by Ada-Europe. It was quite complex and considered far too
radical a change and probably expensive to implement. As a consequence
it was slimmed down considerably. But having been slimmed down it seemed
pointless and was then abandoned. The only part to survive was the idea
of raise with message which became a separate AI and was incorporated
into Ada 2005.